1. Field of the Invention
This invention relates to a heat exchanger of modular type for exchanging heat between several fluids, particularly between two gases.
2. Description of the Prior Art
Tube-and-shell exchangers are known. In the latter, one of the fluids taking part in the exchange passes through tubes, the other fluids passing around the tubes in the shell. The heat exchange surface area per unit volume, called specific surface area, of such exchangers, is generally limited by their constructional requirements since it is difficult to reduce the diameter of the tubes and the spacing therebetween below about 1 cm.
The plate exchangers have larger exchange specific surface areas. In these exchangers the fluids taking part n the exchange circulate on both sides of the different plates but the specific surface is also limited by the requirement of a minimum spacing between the plates.
Other known heat exchangers comprise stacks of perforated sheets, so juxtaposed as to obtain channels by superposition of the perforations, some channels being used for circulating a relatively hot fluid whereas a relatively cold fluid passes through the others; the heat transfer between the channels results from conduction through the material forming at least a portion of said sheets.
The heat exchangers are mostly constituted of metallic materials. In the case where condensation takes place during the heat exchange, as for example when recovering heat from heater fumes, these materials have the disadvantage of being easily corroded.
In a prior patent application, the applicant has already disclosed a heat exchange device of modular structure comprising at least one zone of modular structure, consisting essentially of a stacking of lattices, adapted to tightly join by fitting in one another in superposition, each lattice being formed by intercrossing two series of partition walls assembled by mutual open mortise joining of the parallel walls of the first series with the open mortise joining of the parallel walls of the first series with the parallel walls of the second series at the level of slots provided on one edge (e.g. upper edge) of the walls of the first series and on the opposite edge (e.g. lower edge) of the walls of the second series. The stacking of said lattices forms confined spaces for the circulation of at least two fluids in heat exchange relationship.
As a result of this type of assembling, the exchange zone walls were formed particularly by alternate stacking of lattices of two different types:
The lattices of the first type, wherein the lower edge of the walls of the first series and the upper edges of the walls of the second series are protruding beyond the corresponding faces of said lattices; and
The lattices of the second type, wherein the upper edges of the walls of the first series and the lower edges of the walls of the second series form recesses in the corresponding faces of said lattices;
In addition, the height of the protrusion of the lower edges of the walls of the first series of lattices of the first type, is equal to the recess depth of the upper edges of the walls of the first series of lattices of the second type; and
The protrusion height of the upper edges of the walls of the second series of lattices of the first type is equal to the recess depth of the lower edges of the walls of the second series of lattices of the second type.
In said patent application the exchange zone of modular structure may also consist essentially of a stacking of intercrossing series of walls assembled by mutual open mortise joining of the parallel walls of a series with the parallel walls of the next series at the level of slots provided on both edges of each wall and facing each other. The stacking of the wall series defines confined spaces for the circulation of at least two fluids in heat exchange relationship.
This device, as above described, is formed by simple assembling of elements and provides for an easy adaptation to the geometrical requirements of the user, so that it can be easily inserted in already existing systems. The use of various materials for the manufacture of said device also provides for an easy adaptation thereof to the type of fluids involved in the heat exchange, particularly in view of possible corrosion, for example in heat exchange with condensation.
This device has the further advantage of a large heat exchange specific surface area.
The heat exchange structures of the prior application could be used as well for heat exchanger bodies with two fluids flowing in parallel currents (co-current or counter-current) or in cross-currents, as for fluids input and output ports.